1. Field of the Invention
The present invention is directed toward an electrographic printer having means to prevent slack, backlash and skewing from occurring in the distributed segment of recording material.
2. Description of the Prior Art
In the past various means have been used to properly tension the recording paper used in printers and plotters so that no slack, backlash or edge misalignment occurs between the paper source and a drive roller powered, for example, by a stepper motor. The stepper motor urges the paper through the various stages necessary, in the case of an electrographic printer, for electrically charging the paper during the printing operation. If, for any reason, slack or backlash occurs in the segment of paper located between the paper source and the drive roller, it becomes difficult to print characters of acceptable resolution. The characters that are printed, for example, can either be distorted at the start or finish of the printing operation, or both. The constant starting and stopping of the stepper motor causes extension and compression of the printed characters and thereby results in generally unsatisfactory printouts.
Further, if the paper becomes skewed to either side somewhere between, for example, the paper source and the stylus, or printing, area, and is allowed to remain skewed, the paper can wrinkle and/or tear. Of course, if the paper does wrinkle or tear, or both, it is useless and must be discarded. The printing process must then be repeated.
Various methods have been used in the past in attempts to deal with these problems, but they have generally only met with limited success. These methods have sometimes corrected one of the problems, but have only partially successful in correcting the others.
A further problem area in paper tensioning devices exists because of the different types and weights of recording paper which are widely used. One type is generally identified as roll paper, which is delivered from a rolled source. Another type is commonly called fan-fold and is generally delivered from a stacked source. Up to the time of this inventive contribution, there has been little success in devising a workable and inexpensive method of tensioning, removing backlash and edge-aligning which will work on either of these types of paper. The present invention, as set forth herein, provides a solution to the above-mentioned problems.